Huanglongbing (HLB), which is also known as citrus greening disease, is a fatal disease of citrus trees. Diseased trees are characterized by mottled leaves, poorly developed roots, and produce only a small number of hard, misshapen fruits that fail to ripen properly. Trees infected with HLB die within a few years. HLB is spread by an insect, the Asian citrus psyllid. Insects carrying HLB feed on healthy trees and transmit the bacteria responsible for causing HLB. Infected trees must be removed to protect other citrus trees. The disease is caused by a phloem limited bacteria that cannot be cultured.
HLB is a devastating diseases of citrus that threatens citrus production in the areas in which it occurs. HLB has been identified in Asia, Africa, the Indian subcontinent, and the Arabian Peninsula, Brazil, in the southern United States, and more recently in California. To date, control of the disease has been limited to the eradication of infected citrus plants, and control of the vector with systemic insecticides. Management of HLB has been seriously hampered by the lack of a definitive test that can identify diseased citrus trees. Introduction to identify HLB-infected trees and insects are urgently required.